Effect of thickness and carrier density on the optical polarization of Al{sub 0.44}Ga{sub 0.56}N/Al{sub 0.55}Ga{sub 0.45}N quantum well layers

Journal Article · Wed May 07 04:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4874739· OSTI ID:22273479

Montaño, I.; Crawford, M. H.; Allerman, A. A. ^[1]

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1. Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

The thickness and carrier density of AlGaN quantum well (QW) layers have a strong influence on the valence subband structure, and the resulting optical polarization and light extraction of ultraviolet light-emitting diodes. An ultraviolet-emitting (270–280 nm) multiple quantum well heterostructure consisting of 3 periods of Al{sub 0.44}Ga{sub 0.56}N/Al{sub 0.55}Ga{sub 0.45}N with individual layer thicknesses between 2–3.2 nm is studied both experimentally and theoretically. The optical polarization changes to preferentially polarized perpendicular to the QW plane as the QW thickness increases or the carrier density increases. Calculations show these trends are due to (a) a larger decrease in overlap of conduction band to light and heavy hole envelope functions compared to crystal-field split-off envelope functions, and (b) coupling between the valence subbands where higher heavy hole subbands couple to lower light hole and crystal-field split-off subbands. These changes in the valence band have a profound effect on the optical polarization, emission patterns, and eventual light extraction for ultraviolet emitters at these compositions and thicknesses, and need to be controlled to ensure high device efficiency.

• OSTI ID: 22273479
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 17 Vol. 115; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM COMPOUNDS
CARRIER DENSITY
COMPARATIVE EVALUATIONS
CRYSTAL FIELD
ELECTRONIC STRUCTURE
GALLIUM NITRIDES
HETEROJUNCTIONS
HOLES
LAYERS
LIGHT EMITTING DIODES
POLARIZATION
QUANTUM WELLS
THICKNESS
ULTRAVIOLET RADIATION
VALENCE
VISIBLE RADIATION